Though preventive health is an essential aspect of primary care, prioritizing its delivery has become increasingly difficult. The increased used of technology in the ambulatory setting, such as electronic health records (EHRs) with reminder systems, has provided new tools for effectively delivering preventive health services. To improve the delivery of health maintenance services, we propose to create a standards-based architecture for the transmitting and receiving of preventive health information. Using web services, the architecture will be developed in a modular fashion so that it can be easily modified to be compatible with different EHR systems. The benefits of using such a system include the ability to have a centralized decision support server for processing information and issuing recommendations that can then be applied across various EHR clients. Additionally, the system would allow for the addition of preventive health processes and reminders to EHRs that do not currently have this functionality, without requiring a major software upgrade. The platform-independent, interoperable nature of web services would allow for the system's broad application, while promoting the national IT goals of the use of standards as well as interoperability. Specifically, this project is intended to create a secure, HIPAA-compliant system that focuses on significant preventive health measures and incorporates evidence-based guidelines and epidemiological information to make recommendations. System development will focus on user interface design and workflow integration, two of the biggest barriers to the acceptance to other electronic reminder systems. The success of the system will be measures on several levels, including changes in health quality performance measures, user and patient attitudes toward the system, and the system's technological performance and capabilities. Improving public health is the central focus of this web services-based system. By improving screening and other preventive interventions, the system will reduce the burden of disease in important areas such as cancer and smoking. Demonstrating the success of a standards-based system will also add momentum to the push toward interoperability and may serve as a spur for increased sharing of health related information. The system may also help identify or reinforce priorities in terms of preventive health activities that would be even more effective in improving overall population health.